Functional fluids degrade over time through use. The additives in the functional fluids deplete over the lifetime of the fluid in an engine or other mechanical device. The ability to supply additives to a fluid over its lifetime or use may help preserve and even improve the performance of the functional fluid and the equipment in which it is used. Time release additives for engine oil are known. These additives are typically incorporated into thermoplastic polymers which slowly dissolve into the engine oil, see U.S. Pat. No. 4,075,098. Time release additives have also been incorporated into polymers which are oil-permeable at elevated engine temperatures, see U.S. Pat. No. 4,066,559.
Replenishment of additives in a functional fluid, by using a controlled release gel or other means to add additional additive to the functional fluid, improves the performance of the functional fluid and the device using the functional fluid. Use of controlled release gels, as described in U.S. Pat. No. 6,843,916, has been shown to be an effective means to replenish a lubricant with fresh additives over time. Such gels are formed by incorporating additive components which are compatible with the functional fluid to which the additive is to be delivered into a gel matrix. These gel matrixes often result from the interaction of a basic component and an acidic component, forming the gel.
It would also be beneficial to supply certain additives to functional fluids, but in some cases these additives are not compatible with the functional fluids being used. The additive may be substantially insoluble in, have low solubility in, and/or be otherwise incompatible with the functional fluids in question, making it impossible to effectively use the additive in the functional fluid. The ability to effectively add and/or use such additives in a functional fluid would allow for improvement in the performance of the functional fluid and/or the equipment in which the functional fluid is used. There is a need to identify means of effectively adding and/or utilizing such additives in functional fluid.
The preparation and use of controlled release gels and similar compositions has been previously been described in pending and granted patents, as described above. The use of controlled release gels has been shown to be an effective means to retain critical properties of fresh lubricant by release of fresh additives over time. The conventional application is the use of gel components which are each soluble and/or otherwise compatible in the functional fluid they are to be used with, including the additives desired for controlled release from the gel into the functional fluid. In these gels the main benefit derives from release of fresh compatible additive to replace the depleted additives over the targeted service life of the fluid, providing a practical means for maintaining active additive levels in the fluid.
However, not all lubricant additives are soluble in the functional fluids in which they could be used and not all lubricant additive are soluble to the desired level and/or concentrations. Such substantially insoluble or low solubility additives often include antifoam agents, friction modifiers and other surface active chemicals, like corrosion inhibitors or rust inhibitors. The activity of the chemistry is in some cases (e.g. antifoams) associated with the insolubility. When components are substantially insoluble, it presents a challenge for lubricant formulation, which is constrained by compatibility requirement in the concentrate and the final commercial fluid.
The use of such components in the controlled release compositions and methods of the present invention overcome these constraints and thus allow the use of such substantially insoluble and/or low solubility additives which are active, but otherwise cannot be used in the functional fluids of interest because of compatibility constraints. The present invention can also allow for treatment levels of such additives which are higher than the maximum levels attainable by conventional methods due to these compatibility issues, which in some cases enables the additive to be used in the functional fluid at an optimal level previously unattainable.
Solubility is only one example of incompatibility. Other examples of incompatibilities include those associated with interactions of a supplemental additive with one or more of the other additives in a formulation. Such incompatibilities often result in haze, an increase in viscosity, solid and/or gel formation, and/or deactivation of one or more of the additives in the formulation. Another example of incompatibility is the appearance of a non typical color or dark hue as a result of the addition of a supplemental additive. Such incompatibilities would prevent such supplemental additives from being using in a formulation, even though it presence would provide a performance advantage in the functional fluid.
This practical requirement for an additive to have good solubility and/or compatibility with the functional fluid and concentrate compositions in which it is used applies across functional fluid types and applications. The requirement is necessary for the delivery of the additive to the functional fluid by conventional practices. For example, a functional fluid additive manufacturer would sell a homogeneous additive package of performance chemicals, which may then be added to a base oil to give a final lubricant, which in turn is sold in tanks, drums, cans and plastic containers for final delivery of the lubricant to the equipment to be lubricated. To maintain assurance of performance of the final lubricant, or any other functional fluid, in the equipment in which it is used, the concentrate and the lubricant must remain homogeneous throughout these steps. In other words, all of the additives present must be compatible with each of the various materials it comes into contact with and/or finds itself, from the additive package to the concentrate to the final fluid. This stringent standard greatly limits the choices of and available treatment levels for many performance additives. Many additives that could provide improved performance to a functional fluid are not widely used and/or are not used at the optimal level because the additive does not meet the solubility and/or compatibility requirements discussed above.
Without these solubility and/or compatibility limitations, greater performance and equipment protection might be achievable, including for example extended life of a lubricant or a lubricated piece of equipment such as engines, automatic transmissions, gear assemblies and the like. Improved fuel economy and viscosity stability might be achievable as well. Greater performance may even be achievable with lesser amounts of chemical as well as greater amounts, depending on the selection of the more effective, but otherwise not suitable chemicals from a compatibility or solubility standpoint when delivered in a conventional manner.
The disclosed technology solves the problem of needing to operate within the barriers required by the usual solubility and/or compatibility standard and the limitations it demands. The inventors of the present invention have discovered that through the use of the additive containing compositions of the present invention and the methods of the present invention utilizing the same, they are freed of these encumbrances and are able to achieve the various possible performance enhancements and benefits mentioned above by enabling the use of these classes of additives and treatment levels otherwise forbidden and/or impractical. The devices include containers exposed to the functional fluid in use, also involving a gel or matrix material. The methods also include delivery via addition of solids which are able to melt or dissolve over time, like a bar of soap does in water.